Dry spinning apparatus



Oct. 1943- A. J. MEHLER, J'R

DRY SPINNING APPARATUS Filed June 15, 1 944 Albert JMaleleJg-Ja INVENTOR- BY dwflgg/a Patented Oct. 19, 1948 DRY SPINNING APPARATUS Albert J. Mehler, Jr., Waynes boro, Va., 'assignor to E. I. du Pont de Ner'nour's & Company, Wilmington, Del., a corporationof Delaware Application J due 15, 1944, Serial No. 540,471

This invention relates ,to thedryor evapora tive-spinm'ng of filaments of organic ,acid esters,

of cellulosel More particularly, itrelates to improvements in apparatus for dry-spinning] an acetone solution of cellulose acetate inanevap orative atmosphere containing a [high' concentration of acetone vapor,

spinning technique, large denier filamritsof cellulose acetate which are'slibstantially round and smooth and which have high elongation (45% to 60%) and hence a high degree, of toughness It is known to form, by thedryor evaporative and which are particularly suitedfor. use in rug pile and the like. To produce such filaments it is essentialthat the filament-forming solution be .spun intoi an evaporative atmosphere consisting almost entirely of acetone vapors with some air inthe'immediate vicinity of the spimieret. Various new arrangements, and modificationsv of existing dryspinning cell structures have been developed for v the purpose ofproviding and maintaining such an evaporative atmosphere. However, ;thos e cells which have proven most satisfactory-from the standpoint of the characteristics and quality ofthe yarn producible therefrom featureinevery instance such a complex arrangement of orifices l and by-passes to provide control;:that-operation of the system is delicate in the extreme and generally it is necessaryto adjusteach cell individually and to repeatedly checkthe adjustment in order to secure the desiredyarn properties and spinnability. Moreover, elabora'te, [precautions must be taken to renderlthe cells leak-proof, I

An object of this invention, therefore, is topro' vide means for maintaining the requisite high, concentration of acetone vapors in the dry-spinning cell, and the proper' amount of air about the spinneret, which means is of simple economical construction, does, notinvolve delicate, adjust}, ments, is constant in operation, and is insensitive to minor leaks which may develop in the course oi -I, operation. This and other objects v will, more clearly appear hereinafter,

My invention, which takes "advantzai'gei the fact that acetone vapor (even when hot) has a greater density than air at room temperature,

resides primarily in a" special yarn outlet arrangement or assembly to be attached at the bottom of a standard dry-spinning c 11,' ns'seiit;a11y "this outlet comprises a tubulanmember adapted'to seal the lower end of thecell exceptioran orifice orpassage inthe upper end of the'tubular member, the orifice being of "such size man a-e acetone; vapor flowing theretlirough' of 'its*own 1 Claim. (Cl. 18 -8) hit 2 weight, plus acetonevapor entrained with the yarn, approximately balances the evaporation of acetone from the filaments into the cell. An outlet for the yarn is provided in the lower end of b the tubular member andtwo openings, preferably,

one large and the other small, are provided at diametrically opposed points in the side wall of the tubular member intermediate its ends. In

1 operation the small opening is connected to an l-aspirating system whereby a current of air is cre ated cross-wise of the tubular member which picks up acetone vapor for recovery of acetone, if desired.

From the following description in which is dislo' closed certain embodiments of my invention as well as details oiwhat is believed to be the best mode for carrying out the invention, it will be apparent how the foregoing objects and related ends are'accomplished. The invention will now *be described with reference to the accompanying drawing wherein: t

Figure, 1 is a diagrammatic representation, in

cross-section, of a typical dry-spinning cell embodying the device of my invention;

Figure 2 is an enlarged cross-sectional view of the outer member of the yarn outlet assembly; Figure 3 is an enlarged cross-sectionalview of the inner member of the'yarn outlet assembly;

and I 3d? Figure 4 is aside'view showing a preferred means of removably fitting the inner member of the yarn outlet assembly to the outer'm'ember of said assembly.

Referring now to Figure 1 of the drawing, 5*refere'nce numeral 'l designates a conventional dry-spinning cell having a cold section 2, a jacketed hot section 3, and a spinneret 4 located in" the upper end'of the cell. The usual sight opening 5 customarily used to inspect the spinning ad 'action at the spinneret is provided opposite the spinneret. 1

The lower end of the spinning cell is preferably' providedwith a flange 6 to which is removably attached through thefiange I an outer openended tubular member 8 having a screened side opening 9 (see FiguresZand 3) and a diametrically opposed side opening ill preferably threaded, as' shownffo'r convenient'connection to an aspiratingsystem. The opening 9 is preferably, "but not necessarily, larger in area than opening Ill." Fittedwithinouter tubular member 8 is an inner closed-ended tubular member I l which has outwardly and upwardly turned flange [2 at its 1owerj'end to provide a recessed seat for the lower 3 edge or member 8. The-upper end of tubular member I! is provided with a tapped central opening to receive the threaded skirt I3 of an orifice plate M having a central opening therein. This latter arrangement allows for the easy interand a single tube may be used in place of the double tube arrangement hereinabove described.

To further illustrate the principles and operation of my invention the following specific exchange of orifice plates having different sized 5 amples are given.

with an intermediate gasket l8 forms.agaswtightm seal between the two tubular In ernx q ei s so that the end of the cell is sealed except for the orifice in plate M. Tubular member II is also provided};

with large side opening lgi and small side opening go e e 19: l ss s:

. efe e iietmeri s sel r newed. It i e -1r n qeessr eeiji e, of. t ete if e i e-9 1 19 te: 1 c

oseathat a teres nninahasheen in tiated. 1?

nd. he m em ncmt fien 9 e si ii'alv per 1; athercelllhas h enirea hedlt a i ace tone vapor flowing through the orifice of its own W i ht, p us t e a ount-1 Q a e one... v nq e tra nedby. the yar is l lltlyrless .orsubstan ii 17 1 312 equal .t t e: ratao e a or ti n. 0 a t ne.- i omlth y rnainthe cell W J 'QDY-q a cp um tof concentrated. acetone yapor, extendin irom .the. bottompf the .ceHtowithin the imm diate. vi y of-thespinneret is maintainedurlf aceton enter 91;

the cell faster than it flows out;therb.otto m,.via, the i. yarn. .outlet; orifice... the .excess..,-acetonetwill overflow..thro1.1gh. .the; sight-box opening. Under such conditions. a. large .sighteboxopening shouldn.-

berused... 1.

The: esizetof .Lyarn .outlet, orifice. .to be- .employed depends,.- ofcou'rse, upon the ,sizemf .the .airinlet opening, the size .andnunrben .of filaments; being spun, the concentration and temperature of the spinning bath, the temperatureof. the-cell andthe m,

speedtoflspinning, and .,in.anywcaseis readilyn. determined .by; experimentation .-.follo1 .ing;...the principles previously stated.

The acetone issuing. from the vbottonioif the cell is'subjected tola cross-draft.sufficient-to l l9 13. r-

eters iesl awisn .s qu ery mp thes me...

carryit through theYsmalllside opening in the. yar'nl'outlet'a'ssembly from which pointit is con-.-.. ducted to a suitableunit for the recovery .of ac'etonelfor reuse. The. suction .neededito create the fnecessary cross-draft is slight .and has .no,

sight-box opening. I-Iowever, theair opening may iw firl beat any other .pointin the-cellwall adjacent the pinneretu.

In spinning a pl ral ty of y rnssimultaneo y. in .one.,ce1l. -it is preferred, to use a slot instead f around orificea the bottom of he The-7 m rn wassnunmderthezson it ens of E am l OKQQPQQQQE W353;

slot may,.be made easily adjustable by havingzone side-. .-at.1,east .m dem a m va lesxn ei h ld i 7 p ition by. s r ws. o her..c m ine ans-vsewise.the;tubula1z..m be s mayb o n rectangular o a yeq h red re .rrossesecti mfi 25. ali i sr m q'z e meae is p clin d ,amet-er was used which necessitated increasing Whi eum l} minute-is Eatample I A e li lpse ace at nn n solut pa comprised of 2 5 cellulose acetate-giaboutp iizwof combined 10 went acid): 2.1 2; water, and 72.9% acetone,

heated to 59 C., was extruded through a Ill-hole spinneret, each hole being 0.15 millimeter in diamte'ni andinto a cell constructed as hereinaboy,e de sgrihed andheated to C. The yarn drawn irorn cell through a round yarn fice gqgnillimeters in diameter. The sight-box opening was 2.4 inches in diameter. The-'"extrusion rate 'of the spinning solution was such that with a windup speed of yards per minute, 'a denier-10 vfilament yarn was proess-s men insinua e e 'a pte niei l ams. rad iei: a ti a grmm e o g a ably uniform in quality and y ery few breaks 0 0 39 3.. s ries t eewrsm ihe.-P es. wh h is, .P et .a,-,i qieatir ii -st le.selieoi iiio s-r.

s .s l li lnhl t espe iiiiens p fl emplel I k; ceptthat a sight-box opening of 1 .Q inch innie eme. utle fie 3 i iliiii t rs.

ei :.,ii.. r .Qbtfein raiser swisia itieilr, esemeniprsr issl- V l The spinning" solution'pf Example I was; ex-

truded-thrbugh a'lO-hole spinneret having-holes 0.1-] -milliinete'r in diameter, ja nd the yarn was drawn from' the ellthrough an orifice-5.0;mi1li metrsfi n alarmeter. I The'diameter of t esi ht box opening was l Aeinchesa A 1'70-"deni'r-10 filament yarnhaving proper ties similar to-th0se of "the yarns of iilxamplesf I and T1 was pi'qduced amin qreiiia;

em ar:

ee e ies.s iitieiise .h amiii I ss d P ener t. each/hol .bs-

A l i? .il te iie Example-1H V e ce t-abe whi h s htd-1:.- as TABQ$MZ-P n re e-t e. m; ou

tapithe Sa preva s.

sszrihe esp amen-g :4

with reference to the spinning of an acetone solution of cellulose acetate, it is not so limited but is applicable to the spinning of cellulose acetate dissolved in any of the well known volatile solvents therefor, the hot vapors of which are. heavier than air at room temperature. Also, in place of cellulose acetate other synthetic filament-forming cellulose organic ester materials known to be spinnable by the dryor evaporative-spinning technique may be similarly spun with advantage by employing the apparatus of this invention. Examples of such materials are cellulose propionate, cellulose butyrate, cellulose acetopropionate, cellulose aceto-butyrate.

A principal advantage of my invention is that it avoids the necessity for precise manipulation which attends the operation of prior arrangements involving elaborate systems of orifices, pressure control, and the like.

Furthermore, when the yarn outlet orifice structure of this invention is used, the pressure differential at the upper end of the cell where leaks usually occur is very small; hence, no special precautions against leaks need be taken.

Fewer yarn breaks and greater uniformity in quality of the yarn produced are further advantages attending the use of my invention, and in addition the yarns produced are of greater toughness than yarns heretofore obtainable.

From the economic standpoint, the yarn outlet structure of my invention is simple and inexpensive to manufacture and repair, and it can be applied to present equipment without extensive alterations. Further economies reside in the fact that the apparatus of my invention is stable in operation and requires a minimum of attention and adjustment.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that this invention is not limited to the specific embodiments thereof except as defined in the appended claim.

I claim:

In a spinning cell comprising a sight-box opening at the upper end thereof and adapted for the spinning of cellulose acetate yarn from acetone solutions of cellulose acetate, the improvement 6 which comprises a yarn outlet means at the bottom of the cell, said yarn outlet means comprising an open-ended tube provided at its upper end with an outwardly extending flange through which said tube is removably attached to the bottom end of the spinning cell; a small opening in the side wall of the tube adapted to be connected with an aspirating line, a large screened opening in the side wall of the tube diametrically opposite said small opening, a second tube removably fitted snugly within said open-ended tube in such manner that vapors cannot pass between the walls of said tubes, said second tube being closed at the top except for a removable plate having an orifice therein, said orifice being of such size that the amount of aceton vapor flowing therethrough of its own weight, plus the acetone vapor entrained by the filaments, substantially balances the amount of acetone formed in the cell by evaporation, and a small opening and a large opening in the side wall of the second tube registerin with the small and large openings respectively in said open-ended tube, the lower end of said cell being sealed except for said orifice in said removable orifice plate.

ALBERT J. MEI-lLER, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,902,922 Viviani Mar. 28, 1933 1,950,026 Dreyfus et al. Mar. 6, 1934 2,044,136 Taylor June 16, 1936 2,072,928 Taylor et al. Mar. 9, 1937 2,142,121 Dreyfus Jan. 3, 1939 2,217,707 Samerdyke et al. Oct. 15, 1940 2,341,615 Hoffman Feb. 15, 1944 FOREIGN PAI'EN'IS Number Country Date 368,230 Great Britain Aug. 26, 1930 419,527 Great Britain Nov. 12, 1934 543,062 Great Britain Feb. 9, 1942 

